Resurgent Celtic came from two goals down to salvage a dramatic point in the 91st minute against Rangers to leave Scottish Premiership leaders Hearts with a commanding lead over both Old Firm sides.

A sensational early double from Rangers striker Youssef Chermiti was kick-started by a world-class opener - a wonderful overhead kick reminiscent of Scott McTominay's for Scotland against Denmark late last year.

After claiming a double at Celtic Park at the turn of the year, the Portuguese forward repeated the feat on home soil as a rejigged Celtic defence completely wilted under the pressure.

Dane Murray's botched clearance allowed Chermiti to pounce once again, with the former Everton man slipping past first Julian Araujo then a stunned goalkeeper Viljami Sinisalo, deputising for the ill Kasper Schmeichel.

It was a blow from which Celtic looked unlikely to recover at the break, but manager Martin O'Neill changed the dynamic by throwing on Reo Hatate and Sebastian Tounekti at half-time.

Both were involved in the goal which gave Celtic hope, a move finished when Kieran Tierney headed powerfully in from Benjamin Nygren's cross.

Celtic dominated the second period with Jack Butland denying Daizen Maeda and Luke McCowan, but late drama was to come.

Maeda was denied by an incredible Butland save from point-blank range, but after a video assistant referee review, Dujon Sterling was punished for a handball before his keeper's intervention.

Hatate's penalty and rebound were both saved brilliantly by the Rangers keeper, but the Japanese midfielder bundled the ball in with just a couple of minutes to go - changing not just the scoreline but the complexion of the title race.

The main beneficiaries may well be Hearts whose lead at the top is now six points. Rangers stay second but will be overtaken by their city rivals if Celtic can win their game in hand in midweek at Aberdeen.

This result keeps things nicely at boiling point at the top of the table and increases the likelihood of a four-way tussle for the title, with Motherwell just a couple of points off third-placed Celtic.

Rangers simply blew Celtic away in the opening half hour and were considerably better in every aspect of the game.

The blue half of Glasgow showed better quality, more desire and played by far the better football. Nico Raskin bossed the midfield, while teenage Spurs loanee Mikey Moore was a bundle of tricks and energy.

Plenty of gold-dust was sprinkled on the display, too, from the right boot of Chermiti.

Rangers could easily have been more than two goals ahead at the interval and will now be regretting the fact they could not fashion a bigger cushion.

This would have been a huge win in the context of Rangers' season, a big statement in the race for the title and further evidence of their improvement under Danny Rohl, who has still only lost once in the league since his arrival in October.

A point is far from fatal but it could have been so much better for Rangers.

As for Celtic, the defence of their Premiership crown looked to have completely crumbled in as poor a 45 minutes at Ibrox as they have endured in recent years.

It took Celtic until the second half to turn up for this one, which will not really do with a big derby and a title both on the line.

Manager O'Neill, on his 74th birthday, started Junior Adamu and Alex Oxlade-Chamberlain but rectified those decisions at half-time, from which point he saw a much improved display from his side.

Luckily for the defending champions, the situation was just about recoverable despite the early damage done.

Prior to the break, Celtic looked a shadow of the side that has largely dominated the domestic game for well over a decade.

With Hearts setting a formidable pace at the top of the table, this was either a must-win or a must-not-lose for the men in green and white.

In the end, their determination ensured it was the latter and they are still in an increasingly fascinating title race.

Rangers head coach Danny Rohl tells BBC Scotland: "At the moment, the feeling is more disappointment because you dropped two points after a 2-0 lead.

"It's not about 50 minutes, it's about longer. We had high intensity, we played really nice football, we found our space. It was great.

"In the second half, we were not clinical in possession. We made some wrong decisions then we lose the ball, we give them a little bit of momentum then they score early in the second half and then you know it's 2-1 and they have nothing to lose.

"Finally, it's a draw. It's always a little bit lucky for a team to get a late pen. This is normal, I would say it's the same when we get a pen late in the game. It's about the next game and we have to move on.

Celtic interim manager Martin O'Neill tells BBC Scotland: "It was obviously a great game. We were well and truly second best in the first half, for almost all of it. They got off to a great start.

"The second goal wasn't great play by us, however. It was a long way back at half-time, but this side has shown a great determination, got the ball down and played.

"The second half belonged to us and we got an equaliser which we thoroughly deserved.

"If you're 2-0 down at half-time, you have to question yourself. I spend my life questioning myself, to tell you the truth. But anyway, we pulled it round second half. Great effort by the players, they've shown great spirit."

Rangers have a week to prepare to welcome Celtic to Ibrox once again, this time in the quarter-finals of the Scottish Cup next Sunday (13:00 GMT).

Celtic are on the road again, playing their game in hand at Aberdeen on Wednesday (20:00).